1. Field of the Invention
The present invention relates to an electrophotographic photosensitive member, more particularly to an electrophotographic photosensitive member comprising a photosensitive member containing a disazo pigment having a specified chemical structure. The present invention also relates to an electrophotographic apparatus and a facsimile employing the photosensitive member.
Related Background Art
Known organic photoconductive substances used for electrophotographic photosensitive members include photoconductive polymers typified by poly-N-vinylcarbazole, low-molecular organic photoconductive substances like 2,5-bis(p-diethylaminophenyl)-1,3,4-oxadiazole, combinations of such organic photoconductive substances with a variety of dyes and pigments, and so forth.
Electrophotographic photosensitive members employing an organic photoconductive substance have advantages that the photoconductive members are able to produced at high productivity at low cost, and the color sensitivity thereof is arbitrarily controlled by selecting the employed sensitizer such as a dye and a pigment. Therefore, organic photoconductive substances have comprehensively been investigated. Recently, function separation types of photosensitive members have been developed which have a lamination structure comprising layers of a charge-generating layer containing an organic photoconductive dye or pigment and a charge-transporting layer containing aforementioned photoconductive polymer or a low-molecular organic electroconductive substance, whereby the disadvantage of conventional organic electrophotographic photosensitive members such as low sensitivity and low durability have been remarkably alleviated.
Among organic photoconductive substances, most azo pigments, generally, have superior photoconductivity. Moreover, selection of combinations of an azo component and a coupler component enables control of pigment properties, giving relatively easily a variety of properties of pigment compounds. Accordingly, many azo compounds have been reported as organic photoconductive substances, for example, in Japanese Patent Application Laid-Open Nos. 54-22834, 60-131539, 61-215556, 61-241763, 63-158561, etc.
Recently, with demand for higher picture quality, an organic photoconductive substance is sought which is capable of providing an electrophotographic photosensitive member having high sensitivity and higher potential stability.